题目

Can you imagine living without cars, computers or telephones? Some people in the rain forest and mountains of Venezuela and Brazil do just that. One tribe (部落), the Yanomami , has lived the same way for thousands of years. They only have numbers for one, two and more than two, and they have never invented the wheel. But they have also been called some of “the last free people on earth.”    In the late 1920s, researchers found a tribe of people untouched by modern society. This was the first reported meeting with the Yanomami, who were living deep within the South American jun显微镜观察发生质壁分离的洋葱表皮细胞，不能检视到染色体原因 A．没用染剂染色                 B．试剂破坏染色体结构 C．无染色体形成                 D．显微镜倍率低